Friday I was down in the basement filling a few dents and low spots with thickened epoxy. For thickening I used fine dust from all the sanding we have done. Today I had the pleasure of sanding down the hardened epoxy. Some cunning work with the belt sander saved considerable time, but it is risky business! I worked a lot with a belt sander when I did the Quattro 16 catamaran, so I have a feel for it, but it removes a lot of material really fast! After some longboarding I went over the hull with a random orbital sander with 120grit paper for some minutes to remove the scratches from the 40 grit paper on the longboard. Well, it says 40 grit on the paper but it feels more like 60 grit to me. Frode found a bargain on sandpaper in a shop, and it does the job.
After sanding and cleaning the hull half, we applied a pre-coat of epoxy. The idea is to apply a very thin layer of epoxy to the hull and let it soak in before the glass is put on. That way the wood will soak up less epoxy when putting the glass on, saving considerable weight. We used a new hardener for the pre-coat. This hardener results in a thicker epoxy , so it will not penetrate so deep into the wood. At least that was our theory, we are very, very, excited to check out the results tomorrow! Either it worked well, or we have a large sanding job on our hands..
Today Frode worked mostly on the female mould where we will put the hull half for inside glassing. Things are going forward, and we will only become faster with more experience. E.g. today we found out that you fill all lows first, then sand the hull to shape. Saves you from sanding one extra time to sand down the filler.
I also did some photos with a decent camera today, as compared to the mobile phone cameras we ordinarily uses. Phill, the designer, wanted to see what was up to in somewhat more detail. Feedback was "furniture", which was great to hear, but we know where the faults are :-D
15 comments:
Why pre coat? The glass would fix better if not pre coated.
Man that looks good ! Any difficulties filling the gaps between strips ? Or it was a straight forward job?
We pre coat to stop the epoxy from seeping trough the glass and deep into the wood when glassing. It is an effort to save some weight as the wood can absorb quite a lot of epoxy when glassing. I hope to have time to put on the glass tonight, so we can still get a chemical bond between the layers, but if not, we will wash and sand lightly before we glass.
Filling the gaps was no problem. We did a reasonably tight fit when planking, and just brushed the epoxy on with a brush when the whole hull was planked. The epoxy went into all the gaps and glued the planks together. I think this is a much better way to glue the planks than putting the glue on individually, even if you use a bit of extra epoxy. You dont have to mix small batches, work with a wet edge on the plank and generally create a mess.
The picture might look perfect, but as I wrote in the blog entry, we know where the imperfections are :-)
The epoxy must still be sticy to get a chemical bound, and I have the feeling you are going to use the same amount of resin when you add the both together.
It's your boat, but I prefere to put the glass directly on the naked wood to get a good bound, then give another layer of resin when still sticky to avoid any extra sanding. There will be enough of that later...
Btw. Why glass before you have joined the two halves?
We are following the advice of Bjørn Thomasson, and he has been spot on with all he has said/written so far. He is probably the authority of strip planking small boats today, he even outshines "The gougeon brothers on boat construction" in my opinion.
Ref: http://www.thomassondesign.com/entry.aspx?id=153
Scroll down to "First epoxy coat"
We glass the halves both inside and outside to keep the panels stable and hopefully avoiding warping etc. We will do all 6 side panels before we flip the stations over, and dont want to leave the thin hull panels untreated.
I should perhaps make it clear that we are building in a garage with some heat, so temperature and humidity varies. We will probably have to store the panels somewhere else, another garage perhaps, before we can begin assembling a complete hull.. Hence the concern of warping and movement in the wood.
But thanks for your concern and comments!
My experience comes mostly from France, although Thomasson is not completly unknown at Sydväst. Guess students must have built more than 100 kajaks of his design.
http://uteliv.sydvast.fi/kurser/kajakbygge.htm
Right, so his procedure is not unknown to you then? I think his methods are well tested so I am not too afraid of following his descriptions. So far it has all been good.
If you think pre-coating is radical, wait until you see us putting on the glass in strips to make it cover the planks +-45 degrees. That will be radical, and I am afraid of the amount of sanding that experiment might result in. Well well, we are building boats for usage, not a furniture for the living room. We will probably go for a clear finish with only the bottom faired so the penalty is perhaps not that large.. Perhaps we are doing too much untried stuff with these boats, who knows?
I like radical solutions myself and I like your idea of "strip planking". I am making a mast for a Pixie at the moment in strips of 4 mm ply!! If it works the next one will go on my Blade.
And somebody has to do the untried stuff.
A ply-strip mast?? That is really interesting. Something that really is worthy of a thread on the building forum on catsailor.com!
Looking awesome!
I'm following your blog 'cuz I expect to do a similar project in my near future.
I'm thinking of adopting this method ... http://www.multihulldesigns.com/pdf/cm33.pdf ... for a blade build (hope being the "torture" isn't as bad ...)
Curreyr,
if you plan on anything else than homebuilding the Blade16 in stressed ply, you should contact Phill Brander. Plan availibility is very, very, limited so dont be surprised if Phill will only sell you the regular stressed ply plans. There are very good reasons from the designers side for these limitations.
yea, I would definetely discuss it with him prior.
Hei Rolf. Dette ser spenende ut. Håper dere stiller i Røyken Hootfoot Jollemaraton til høsten.
PS den er flyttet til lørdag 13 september
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